Tag: dynamic

Emergency Power System

Posted on by lechuck park

This image shows a diagram of an Emergency Power System and the characteristics of each component.

Overall System Structure

At the top, the power grid is connected to servers/data centers, and three backup power options are presented in case of power supply interruption.

Three Backup Power Options

1. Generator

  • Long-term operation: Unlimited operation as long as fuel is available
  • Operation method: Engine rotation → Power generation
  • Type: Diesel engine generator
  • Disadvantages:
    • Start-up delay during instantaneous power outages
    • Start-up delay, noise, exhaust emissions
    • Periodic testing required
    • Requires integration with ATS (Automatic Transfer Switch)

2. Dynamic UPS

  • Features:
    • Uninterrupted/Long-term operation (until diesel engine starts)
    • Flywheel kinetic energy storage
    • Combined generator and diesel engine
  • Advantages: Seamless power supply without STS (Static Transfer Switch)
  • Disadvantages: High initial cost, large footprint, noise

DR (Diesel Rotary) UPS: A special form of Dynamic UPS that provides uninterrupted power through flywheel energy storage technology.

3. Static UPS

  • Operation time: Instantaneous/Short-term (typically 5-15 minutes)
  • Power quality: Clean power supply
  • Configuration: Battery(DC) → Inverter(AC) → Rectifier
  • Features:
    • Millisecond-level instant transfer
    • Battery life 3-5 years, replacement costs, heat generation issues

Key Characteristics Summary

Generators can operate long-term with fuel supply but have start-up delays, while Static UPS provides immediate power but only for short durations. Dynamic UPS (including DR UPS) is a hybrid solution that provides uninterrupted power through flywheel technology while enabling long-term operation when combined with diesel engines. In actual operations, it’s common to use these systems in combination, considering the advantages and disadvantages of each system.

With Claude

Recent Memory Control

Posted on by lechuck park

From Perplexity with some prompting
The image illustrates a change in memory object management in recent Linux kernels, focusing on the transition from fixed-size page memory blocks to dynamic-size object memory blocks.

Left: Fixed-Size Page Memory Block

  • Page Memory Block: Typically uses fixed-size blocks, generally 4KB in size.
  • Meta Table: Managed by simple ID values (e.g., 1, 2, 3, 4, 5), allowing for straightforward and efficient control.

Right: Dynamic-Size Object Memory Block

Meta Table: Requires both ID values and sizes (e.g., (1, size), (2, size)), necessitating more complex computation and larger metadata tables.

Object Memory Block: Utilizes blocks of varying sizes to accommodate different memory object sizes.

This transition reflects a shift towards more flexible memory management, allowing for better utilization of memory resources by accommodating objects of different sizes. However, it also introduces increased complexity in managing these memory allocations.